Process for producing aldehydes



Patented Dec. 8, 1942 UNITED STATES PATENT OFFICE PROCESS FORPRODUCINGALDEHYDES No Drawing. Application April 28, 1942, Serial No. 440,878

(Granted under the act of March 3, 1883, as amended April 30, 1928; 3'700. G. 757) 3 Claims.

This application is made under the act of MarchB, 1883, as amended bythe act of April 30, 1928, and the invention herein described andclaimed, if patented, may be manufactured and used by or for theGovernment of the United States of America for governmental purposeswithout the payment to us of any royalty there- This application is inpart a continuation of our copending application Serial No. 302,602filed November 2, 1939, Patent No. 2,285,059.

This invention relates to organic compounds and is directed moreparticularly to the production of derivative from compounds comprisingan acyclic carbon chain containing at least three carbon atoms.

According to the present invention the ethylenic linkage CH=CH) of anunsaturated acyclic carbon chain containing at least three carbon atomsis converted to an alpha-glycol group, and aldehydes are produced byoxidation of compounds containin an alpha-glycol group with concomitantcleavage of the acyclic carbon chain between the carbon atoms of thealphaglycol grouping.

Our process is applicable to the production of alpha-glycols and ofaldehydes from unsaturated alcohols, unsaturated fatty acids,unsaturated carb'oxylic esters, and from materials consisting of orcomprising such unsaturated compounds.

Thus we may use as starting materials such relatively inexpensive andreadily available substances as ester-type Waxes and oleaginousmaterials of animal or vegetable origin for example lard, lard oil,cottonseed oil, peanut oil, olive oil, or fractions thereof obtainablefor instance by crystallization or solvent extraction. Our invention isalso applicable to the treatment of constituents or derivatives of thesenatural products, for instance of unsaturated fatty acids like oleic,ricinoleic or lineoleic acid, their esters with polyhydric alcohols suchas the glycerides, or with monohydric alcohol like methyl, ethyl,propyl, butyl esters.

Unsaturated alcohols containing ethylenic linkages such as for exampleoleyl alcohol or esters of these alcohols with fatty acids may also beconverted to aldehydes or to intermediate products by our process.

Our process is not limited, however, to the treatment of naturallyoccurring compounds or of their derivatives but may be applied to thetreatment of any aliphatic unsaturated alcohol, carboxylic acid orcarboxylic acid ester containing an ethylenic linkage and at least 3carbon atoms, and to the products obtained from the aforementionedaliphatic compounds by conversion of the ethylenic linkage to analpha-glycol group, by any suitable procedure.

The aldehydes produced by our process may also contain other functionalgroups in their molecule such as for example, ketone, aldehyde,carboxyl, or hydroxyl groups, depending upon the nature of the startingmaterial.

The aldehydes obtained by our process are useful as components orintermediate products in the manufacture of various products such as forexample perfumes, flavoring materials, vuloanization accelerators,pharmaceuticals, plastics, resins, plasticizers, artificial fibers andother synthetic products.

' According to the present invention the unsaturated compounds areh'ydroxylated by a treatment with a mixture of 30% hydrogen peroxide andglacial acetic acid, thereby converting the ethylenic linkages toalpha-glycol groups according to the following equation:

violent exothermic reaction occurs which is extremely difficult tocontrol especially when operating. on a fairly large scale. Thetemperature of the mixture rises rapidly and violent ebullition takesplace. not only causes considerable-lossesof hydrogen peroxide whichdecomposes at higher temperatures, but also promotes the formation ofacetylated alpha-glycol groups which do not readily undergo scission onsubsequent treatment.

We have discovered that the hydroxylation reaction proceeds rapidly atmoderate tempera-' tures if prior to the addition of the unsaturatedcompound the mixture of glacial acetic acid and 30% hydrogen peroxide ismaintained at 80-85 C. for about one hour, and then cooled tosubstantially room temperature. When the unsaturated compound isintroduced into this cooled mixture, the hydroxylation reaction proceedsrapidly and is completed within a relatively short If the mixture isheated the reaction This sudden evolution of heatperiod of time withoutapplication of heat. Under these conditions the exothermic nature of theprocess is mitigated to such an extent that most of the heat evolved isdissipated by radiation and whenever necessary the temperature of thebatch may be readily controlled by adequate cooling.

The hydroxylated compounds are then converted to aldehydes by treatingthem with red lead (Pb304) and glacial acetic acid. 1

This step of our process can be carried out without isolating thehydroxylated compounds from the products of the hydroxylating reaction,and may be effected by adding the necessary amount of glacial aceticacid and red lead to the mixture.

Red lead appears to react with acetic acid to form lead tetracetatewhich interacts as rapidly as it is formed with the compound containingan alpha-glycol group, splitting the carbon chain between the adjacentcarbon atoms linked to the hydroxyl groups and yielding aldehydesaccording to the following equation wherein the reaction is illustratedas applied to a compound comprising one. alpha-glycol group.

OH OH Pb( C O CHah-HCHaC O OH The method of our invention thus obviatesthe necessity of isolating and purifying the unstable lead tetracetate.

When our process is operated without isolating the hydroxylatedintermediate product or products the hydrogen peroxide present in thereaction mixture has no detrimental efiect on the process and isbelieved to be decomposed by the action of red lead prior to theformation of aldehydes.

In some cases it may be advantageous to isolate the hydroxylatedcompounds, or to subject them to a thermal treatment in the presence ofalkalies, thereby effecting the hydrolysis of any acetyl groups whichare usually formed when the hydroxylation is performed in the presenceof acetic acid. Since lead tetracetate does not react with alpha-glycolgroups containing substituted hydroxyl groups the elimination of acetylgroups increases the yields of aldehydes on subsequent treatment withred lead and glacial acetic acid.

It is to be understood of course that our invention is not limited tothe treatment of hydroxylated compounds obtained by any of the foregoingprocedures. The reaction with red lead and glacial acetic acid isapplicable to the production of aldehydes from compounds containingalpha-glycol groups produced by other methods, such as for exampletreatment of unsaturated compounds with potassium permanganate or withpersulfuric acid.

The aldehydes obtained may be isolated by any suitable means such as forinstance steam distillation or solvent extraction.

Acetic acid and lead acetate may be recovered, and also other byproductsof the process such as for example glycerol which is formed when theprocess is applied to the treatment of glyceryl esters.

As illustrative embodiments of a manner in which our invention may becarried out in practice the following examples are given:

Example 1 1800 cc. of glacial acetic acid and 567 grams of 30% hydrogenperoxide were mixed together and heated on the steam bath atapproximately C. for one hour. The mixture was then cooled to about 25C. and added to 706 grams of oleic acid. With occasional agitation theensuing exothermic reaction was allowed to proceed without applicationof heat. In 40 minutes the temperature had risen to 65 C. and atthattemperature the oily layer disappeared and the solution becamehomogeneous and clear. The temperature then began to fall very slowlyand the mixture was allowed to stand over night at room temperature. Itwas filtered cold to remove a small quantity of a waxy solid, pouredinto 6,000 cc. of hot H20, and the aqueous layer was siphoned off anddiscarded. The residual oil was dissolved in 750 cc. of 6N NaOH and 4000cc. of water and heated two hours on the steam bath. It was then heatedto boiling, removed from the heat and acidified with 6N HCl. The oilthrown out of the hot solution solidified on cooling, was separated fromthe aqueous layer, remelted and thoroughly washed with about 3000 cc. ofboiling water. The mixture was allowed to cool, the solidified productseparated, dried for a day over anhydrous calcium chloride andrecrystallized from alcohol. Yield 353 grams of 9,10-dihydroxystearicacid: M. P., 89-90 C. Neutralization equivalent. 316.4 (theory 316.3).

63 grams of this purified 9,10-dihydroxystearic acid were dissolved in500 grams of glacial acetic acid at 55-65 C. Maintaining the temperaturewithin that range, 151 grams of finely powdered, ordinary red lead(Pb304) were added in small portions. Each successive portion was addedonly after the previous one had been completely decolorized. When allthe red lead had been added the solution was diluted with 500 cc. ofwater and steam distilled. The pelargonic aldehyde, a colorless oil, wasseparated from the distillate mechanically, or by extracting with animmiscible solvent, such as ether, washed with dilute alkali, then withwater and dried. 'The' Example 2 Dihydroxystearic acid was prepared byhydroxylating 282 grams of oleic acid as described in Example 1, butomitting the final recrystallization from alcohol. The product afterbeing, airdried weighed 288 grams. This material was dissolved in 2200cc. of glacial acetic acid, heated to 55-65 C. and while maintaining thetemperature within that range, 754 grams of red lead (Pb304) were. addedin smallv portions. When the'reactionwas complete the reaction mixturewas diluted with 1500 cc. of water-and steam distilled.

The pelargonic aldehyde was separated from the distillate by extractionwithether, and purified by consecutive washing with water, sodiumbicarbonate solution and again with water, and then dried over anhydrouscalcium sulfate. The ether was removed by evaporation under reducedpressure Yield 51 grams of pelargonio aldehyda.

or 36% of theory, based onthe oleic acid used.

The steam distillation residue was extracted with'ether, washed free oflead with water, the ether was removed by evaporation under reducedpressure, and the residue was dissolved in sufficient sodium hydroxideto give a solution having a pH value of 8-9. A solution of 92 grams ofpotassium permangante in 1100 cc. of water was added at room temperatureas rapidly as possible to this alkaline solution with vigorousagitation, but with care to prevent loss by foaming. The temperature ofthe mixture rose rapidly to about 70 C. The stirring was continued untilfifteen minutes after the disappearance of the permanganate color. Afterstanding over night the manganese dioxide was removed by filtration,washed thoroughly with boiling water, and the combined filtrate andwashings were acidified with sulfuric acid and chilled in therefrigerator. The small quantity of oil, which separated onacidification, solidified and was easily removed mechanically. Thecrystals of azelaic acid which also separated on cooling wereredissolved by heating the solution on the steam bath and the solutionwas concentrated to about two liters, boiled a short time with a smallquantity of decolorizing charcoal, filtered and cooled in therefrigerator'. The crystals of azelaic acid were filtered and washed,and recrystallized from water. Yield 11 grams, 6% of the theory, basedon oleic acid used. M. P. 104-106" C.

Example 3 720 cc. of glacial acetic acid and 225 grams of 30% hydrogenperoxide were mixed and heated for one hour at 80-85 C. The mixture wascooled to and 282 grams of oleic acid were added to it at thattemperature. The ensuing exothermic reaction was allowed to proceed withoccasional agitation. In minutes the temperature had risen to 65 C. andthe solution was homogeneous. After about 15 minutes the temperaturebegan to fall slowly. After standing over night this reaction mixturewas diluted with 1480 cc. of glacial acetic acid, heated to 55-65 C. and754 grams of finely powdered red lead were added in small portions. Whena test indicated that the oxidizing agent was exhausted the mixture wassteam distilled. The pelargonic aldehyde was extracted from thedistillate with ether. The ether solution was washed with water,saturated sodium bicarbonate solution, again with water, dried overanhydrous calcium sulfate, filtered and the ether removed byevaporation. Yield 33 grams, 23% of theory.

Example 4 720 cc. of glacial acetic acid and 225 grams of 30% hydrogenperoxide were mixed and heated for one hour at 8085 C. The solution wascooled to 25 C. and 310 grams of ethyl oleate were added. The mixturewas agitated occasionally and in the course of an hour the temperaturerose to 61 C. but the mixture did not become homogeneous. An additional400 cc. of glacial acetic acid was heated to 60 C. and added which 5K;33% of theory. The steam distillation residue ether solution was driedover anhydrous calcium sulfate, filtered, and the ether removed byevaporation. Yield of pelargonic aldehyde, 4'? grams,

was extracted'with ether. This ether solution was treated in the samemanner as was the ether extract of the distillate. The residue wasvacuum distilled. Yield of the pure ethyl ester of azelaic halfaldehyde,'25 grams, 12.5% of theory.

Example 5 Both the high-melting and low-melting forms of the ethyl esterof dihydroxystearic' acid were I prepared by esterifying with ethylalcohol, the crude dihydroxy'stearic acids obtained by hydroxylatingoleic acid with potassium'permanganate in aqueous alkaline solution, and30% hydrogen peroxide in acetic acidsolution, respective- :ly. In thesubsequent treatment no difierencc was observed in the behavior of thetwo forms of the ester. 69 grams of ethyl-9,10-dihydr'oxystearate weretreated with red lead in the same manner as described in Example 1.Pelargonic aldehyde was recovered as a colorless oil from the steamdistillate. The yield was 25 grams,.88% of theory. The residue yieldedabout 33 grams, 83% of theory, of pale yellow oil, the ethyl ester ofthe half-aldehyde of azelaic acid.

Pelargonic aldehyde and the methyl ester of the half-aldehyde of azelaicacid were obtained by substituting in Examplese and 5 ethyl oleate andthe ethyl ester of dihydroxystearic acid by the equivalent amounts ofmethyl oleate and the methyl ester of dihydroxystearic acid.

Example 6 225 grams of 30% hydrogen peroxide and 820 cc. of glacialacetic acid were mixed and heated gave a clear, homogeneous solution.After the solutionhad stood over night, 1080 cc. of glacial acetic acidwere added, and the solution was heated to 55-55 C. The oxidation withred lead was carried out as described in Example 3. The clear solutionwas diluted with 1000 cc. of water and steam distilled. The distillatewas extracted with ether, the ether solution was washed twice withWater, then with sodium bicarbonate solufor one hour at '85 C. Thesolution was cooled to 25 C. and mixed with 311 grams of castor oil. Themixture was agitated occasionally and the temperature rose to 66 C. inabout 30 minutes becoming homogeneous at about 59 C. The temperaturebegan to fall slowly and the solution was stirred mechanically about twohours and allowed to cool to room temperature. An additional 1380 cc.portion of glacial acetic acid was added, the solution was heated to5565 C. and 754 grams of finely powdered red lead were added in smallportions. The reaction mixture was steam distilled and the distillatewas extracted with ether. The ether solution was washed with water,sodium bicarbonate solution and again with water, dried with anhydrouscalcium sulfate, and evaporation of the ether yielded 47 grams ofalpha-nonenaldehyde.

The residue was extracted with ether, the ether solution was washed freeof lead, and the ether evaporated. The residual oil was dissolved in1000 cc. of glacial acetic acid and 225 grams of 30% hydrogen peroxidewere added. The mixture was allowed to stand about 24 hours then heatedon the steam bath until the temperature stopped rising and then removed.The acetic acid was distilled off with steam, the supernatant aqueouslayer was poured off and the residue was neutralized with 25% sodiumhydroxide solution. The mixture was refluxed three hours with a 1000 cc.excess of 6N NaOH. It was then acidified with sulfuric acid while hot,and the aqueous layer was .immediately removed by filtration. Thefiltrate was boiled with a small portion of a V decolorizing charcoal toremove the small quantity of oil which came through the filter, filteredtion and again with water until neutral. The

hot and allowed to cool. The azelaic acid separated as small, whitecrystals. Yield about 26 grams.

Example 7 720 cc. of glacial acid and 225 grams of 30% hydrogen peroxidewere mixed together and heated on the steam bath at approximately 85 C.for one hour. The solution was then cooled to room temperature and addedto 268.5 grams of oleyl alcohol. With occasional stirring the ensuingexothermic reaction was allowed to proceed without application of heat.In 30 minutes the temperature had risen to 72 C. and the solution washomogeneous and clear. The temperature then began to fall very slowlyand the mixture was allowed to stand over night at room temperature. Thesolution was then poured into 2400 cc. of hot water and the aqueouslayer was discarded. The residual oil was neutralized with 1N alcoholicKOH and an additional 1000 cc. of 1N alcoholic KOH was added. Afterrefluxing for two hours, the alcohol was removed and. the product wasseparated as an oil by dilution with hot water; followed by vigorousstirring. The aqueous layer was discarded and the oil was washedthoroughly with hot water. After cooling, the solidified oil wasseparated from the wash water, broken up and air-dried. The dry productwas crystallized from ethyl acetate. Yield, 138 grams of9,10-dihydroxyoctadecanol-l (46%).

The oxidation of 9,IO-dihydroxyoctadecanol-l was carried out asdescribed in Example 1 for 9,10-dihydroxystearic acid using 151 gram of9,10-dihydroxyoctadecanol-1, 1230 cc. of glacial acetic acid and 377grams of red lead. When all the red lead had been added, the reactionmixture was diluted with a large excess of water and extracted twicewith ether. The combined ether extracts were washed with water untilfree from lead salts and acetic acid, dried over calcium sulfate, andthe ether was evaporated. The residue was vacuum distilled yieldinggrams of pelargonic aldehyde, yield based on 9,10-dihydroxyoctadecanol-land 40 grams of 9-hydroxypelargonic aldehyde, 51% yield on the samebasis.

Example 8 9,10-dihydroxyoctadecanol-l was prepared as described inExample 7, except that the recrystallization from ethyl acetate wasomitted. The product after being air-dried weighed 270 grams. Thismaterial was oxidized as described in Example 2 for crude9,10-dihydroxystearic acid. When all the red lead had been added thereaction mixture was treated as described in Example 7. In this manner,38 grams of pelargonic aldehyde and 36 grams of 9-hydroxypelargonicaldehyde were obtained.

We claim:

1. The process for producing aldehydes which comprises hydroxylating theethylenic linkage of.

an unsaturated aliphatic alcohol containing eighteen carbon atoms byreacting said alcohol at temperatures ranging from 25 to C. with theproduct obtained by heating a mixture of glacial acetic acid and 30%hydrogen peroxide solution for substantially one hour at temperaturesranging from 80 to C. and subsequently reacting the hydroxylatedcompound with red lead and glacial acetic acid at temperatures ofsubstantially 55-65 C.

2. The process for producing aldehydes which comprises reacting analiphaticcompound containing eighteen carbon atoms, an alpha glycolgroup and an alcohol group with red lead and glacial acetic acid attemperatures of substantially 55-65 C.

3. The process as defined in claim 1, wherein the unsaturated aliphaticalcohol is oleyl alcohol.

JOHN T. SCANLAN. DANIEL SWERN.

